libbpf-tools: fix cpufreq.bpf.c and update cpufreq for libbpf 1.0

Switch to libbpf 1.0 mode and adapt libbpf API usage accordingly. Also fix cachestat.bpf.c by adding a BPF assembly trick to ensure that BPF verifier sees proper value bounds for cpu ID. Signed-off-by: Andrii Nakryiko <[email protected]>
weibang6liu · Dec 20, 2021 · f2006ea · f2006ea
1 parent 4970d23
commit f2006ea
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Showing 2 changed files with 15 additions and 11 deletions.
diff --git a/libbpf-tools/cpufreq.bpf.c b/libbpf-tools/cpufreq.bpf.c
@@ -17,11 +17,21 @@ struct {
  __type(value, struct hist);
 } hists SEC(".maps");
 
+#define clamp_umax(VAR, UMAX) \
+ asm volatile ( \
+ "if %0 <= %[max] goto +1\n" \
+ "%0 = %[max]\n" \
+ : "+r"(VAR) \
+ : [max]"i"(UMAX) \
+ )
+
 SEC("tp_btf/cpu_frequency")
 int BPF_PROG(cpu_frequency, unsigned int state, unsigned int cpu_id)
 {
  if (cpu_id >= MAX_CPU_NR)
  return 0;
+
+ clamp_umax(cpu_id, MAX_CPU_NR - 1);
  freqs_mhz[cpu_id] = state / 1000;
  return 0;
 }
@@ -36,6 +46,7 @@ int do_sample(struct bpf_perf_event_data *ctx)
 
  if (cpu >= MAX_CPU_NR)
  return 0;
+ clamp_umax(cpu, MAX_CPU_NR - 1);
  freq_mhz = freqs_mhz[cpu];
  if (!freq_mhz)
  return 0;

diff --git a/libbpf-tools/cpufreq.c b/libbpf-tools/cpufreq.c
@@ -102,10 +102,8 @@ static int open_and_attach_perf_event(int freq, struct bpf_program *prog,
  return -1;
  }
  links[i] = bpf_program__attach_perf_event(prog, fd);
- if (libbpf_get_error(links[i])) {
- fprintf(stderr, "failed to attach perf event on cpu: "
- "%d\n", i);
- links[i] = NULL;
+ if (!links[i]) {
+ fprintf(stderr, "failed to attach perf event on cpu: %d\n", i);
  close(fd);
  return -1;
  }
@@ -176,7 +174,7 @@ static void print_linear_hists(struct bpf_map *hists,
 
  printf("\n");
  print_linear_hist(bss->syswide.slots, MAX_SLOTS, 0, HIST_STEP_SIZE,
- "syswide");
+  "syswide");
 }
 
 int main(int argc, char **argv)
@@ -194,14 +192,9 @@ int main(int argc, char **argv)
  if (err)
  return err;
 
+ libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
  libbpf_set_print(libbpf_print_fn);
 
- err = bump_memlock_rlimit();
- if (err) {
- fprintf(stderr, "failed to increase rlimit: %d\n", err);
- return 1;
- }
-
  nr_cpus = libbpf_num_possible_cpus();
  if (nr_cpus < 0) {
  fprintf(stderr, "failed to get # of possible cpus: '%s'!\n",